Glucopyranoside methyl 4,6-dichloro-4,6-dideoxy

Treatment of l,4 3,6-dianhydro-D-glucitol with boron trichloride gives l,6-dichloro-l,6-dideoxy-D-glucitol (20). Although methyl 6-chloro-6-deoxy-a-D-glucopyranoside (isolated as the tribenzoate) could be isolated from the reaction of methyl 3,6-anhydro-a-D-glucopyranoside with boron trichloride (21), the application to the isomeric furanoside derivative led to complex results. 

Reactivity at 0-3, in addition to that at 0-4 and 0-6, was observed with methyl )3-D-galactopyranoside, which, when treated with sulfuryl chloride, yielded methyl 3,4,6-trichloro-3,4,6-trideoxy-/J-D-allopyranoside 2-(chlorosulfate) in 56% yield.352 In contrast, under similar conditions, methyl a-D-galactopyranoside gave352 methyl 4,6-dichloro-4,6-dideoxy-a-D-glucopyranoside 2,3-di(chlorosulfate). Further examples of the dependence of the reactivity on the configuration of C-l are the conversion of methyl 4,6-0-benzylidene-/3-D-glucopyranoside into methyl 4,6-0-benzylidene-3-chloro-3-deoxy-/3-i>allopyranoside by sulfuryl chloride,352 and of methyl 4,6-0-benzylidene-a-D-glucopyranoside, under similar conditions, into the 2,3-di(chlorosulfate).355... 

The reaction of sulfuryl chloride with carbohydrates to give chloro-deoxy derivatives has been reviewed briefly in this Series.98 The reaction of sulfuryl chloride with monosaccharides has been shown to afford products in which the secondary hydroxyl groups are replaced by chlorine with inversion of configuration.68-75 Jones and coworkers reported that the reaction of methyl a-D-glucopyranoside with sulfuryl chloride and pyridine in chloroform at room temperature proceeds by way of the 4,6-bis(chlorosulfate) by an Sn2 process, with chloride as the nucleophile, to give methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside 2,3-bis(chlorosulfate).74... 

An example of the inhibitory effect of a vicinal, axial substituent was provided by the observation25 that, whereas methyl 4,6-dichloro-4,6-dideoxy-/3-D-glucopyranoside 2,3-di(chlorosulfate) readily under-... 

An X-ray crystallographic analysis has been performed44 on methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside prepared by way of reaction of methyl a-D-glucopyranoside with sulfuryl chloride the molecule has the Cl (d) conformation, and the bond distances and valency angles are similar to those in simple sugars. 

In 1921 Helferich [34J found that treatment of methyl a-D-glucopyranoside 18 with sulfuryl chloride in a mixture of pyridine and chloroform at 5°C afforded a compound, the structure of which was established several years later [37,38] to be that of methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside 2,3-cyclic sulfate (19 Scheme 3). The cyclic sulfates are readily cleaved by dilute alkalis, or by methanolic ammonia, to give the salt of a monosulfate the hemi-ester is then desulfated by acid to yield the chlorodeoxy sugar [35,36]. Both of these reactions occur with retention of configuration [37]. 

Methyl a-D-glucopyranoside (18, 40 g) was converted into methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyranoside 2,3-di(chlorosulfate) (20,78 g), by the method of Jennings. and Jones [39,40]. The syrupy material was dissolved in methanol (1200 mL), and a golution of sodium iodide [63 g in 160 mL of methanol-water (1 1, v/v)] was added. The gQlgtion was neutralized with sodium hydrogen carbonate. The insoluble material was SSHoSed by filtration, and the filtrate was concentrated to dryness. The residue was... 

Dideoxy-D-xy/o-hexose (163) was obtained from methyl a-D-glucopy-ranoside via 2,3-di-(3-benzoyl-4,6-di-(9-/ -tolylsulfonyl-v-D-glucopyranoside (162, Scheme 48)237 or via methyl 4,6-dichloro-4,6-dideoxy-a-D-galactopyrano-side.238... 

C7H12CI2O4 Methyl 4,6-dichloro-4.6-dideoxy-a-D-glucopyranoside DDGLPY 31 366... 

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